Indicating, recording, and/or controlling apparatus



A ril 5, 1938.. R. w. oss ET AL INDICATING, RECORDING AND/OR CONTROLLINGAPPARATUS Filed April 18, 1936 7 Shets-Sheet 1 ,INVENTORS Raymond W.Ross 5 0rd. H..Seber/k1gen,deceu:d Sophie Seberhaqen, 'execuirix by Mar!WM ATTORNEY April 5, 1938. R. w. R088 ET AL 2,113,069

INDICATING, RECORDING, AND/OR CONTROLLING APPARATUS Filed April 18, 19367 Sheets-Sheet 2 8 O a O r aka-VF o \M v m o mwhwmwm e Q Q INVENTORSRaymond M Ross Sigurd H- Seberhagen, deceased Sophie Seber'hagen,execuir'ix Br W a, waif ATTORNEY.

A ril 5, 1938. R. w. R055 ET AL 2,113,069

INDICATING, RECORDING, AND/OR CONTROLLING APPARATUS Filed April 18, 19367 Shets-Sheet s IN EN ORS Raymond W. Ross SLgur'd H. Seberhagen deceasedSophie Seberhaqen, executrix ATTORNEY.

'Aprii 5, 1938.

R. W. ROSS AL INDICATING, RECORDING, AND/OR CONTROLLING APPARATUS 7Sheets-Sheet 4 Filed April 18,- 1956 INVENTORS Raymond W- Rgss Sigurd.H. .Seberhaqemdecanm Sophia Seberhagemexecutm'x 9 W 1.03m

ATTORNEY.

April 5, 1938 I R. WJROSS ET AL 2,113,069

INDICATING, RECORDING, AND/0R CONTROLLING APPARATUS- Filed April 18,1936 7 Sheets-Sheet 5 JZL INVENTORS Raymond W. Ross Sigurd H.Serbsvhagerwleceased Sophie Seber'hdgcn,cxecvtrix Mica-7a.;

ATTORNEY.

April 5, 1938. w; R055 ET AL INDICATING, RECORDING, AND/OR CONTROLLINGAPPARATUS Filed April 18, 1936 7 She ets-Sheet 6 m. mu S m & m N Tsw NuRa W 3 N.WS.M I M w J. m wh B ygp a O RS5 ATTORNEY.

A ril 5, 1938. R. w. R055 El AL 2,113,069

INDICATING RECORDING, AND/OR CONTROLLING APPARATUS Filed April 1a, 19567 Sheets-Sheet v FIGIBA INVENTORS Raymqnd M Ross Scgurd H.Seber'hagemdermsed Sophie Sebrhaqemexecvtrlx 7 Mwkflu ATTORNEY.

named A s, was

I INDIOA'IING,

ll. Pa by Sophisdelphia, Pass-signer Ecol-DING, AND/OI GON- m TUB,mcuirhl'hilatolieadsandNorthi-up company, Philadelphia, Pa-,acorporation of was... in is, me. Serial No. 15,208

This invention relates to exhibiting instruments and apparatus forindicating, recording, controlling or otherwise measuring the magnitudeof any predetermined condition; and more particularly to an apparatusfor use in connection with a measuring circuit and including means forintermittently rebalancing the same, of such type, for example, as shownand described in United States Letters Patent No. 1,935,732, grantedNovember 21, 1938, upon the application of L. Y. Squibb.

This application is a continuation-in-part of 1 copending applicationSerial No. 2,972, filed January 22, 1935, for Indicating, recordingand/or controlling apparatus. a

While this invention is of general application, it is particularlysuitable for application to multiple-record indicating, recording and/ormeasuring apparatus for use in connection with a measuring circuit andincluding means for periodically recalibrating the measuring circuit;this invention relates further to the several component operatingmechanisms of such an apparatus by means of which the various portionsthereof are maintained insynchronism and the phase therebetweenaccurately adjusted, thus avoiding interference of the separatemechanisms or misleading or irregular records or indications.

More specifically, this invention comprises indicating, recording,controlling and/or measuring apparatus including a primary membermovable in response to the magnitude of a condition under measurement,as determined by a measuring circuit; a continuously operated drivingelement or power mechanism, and a mechanical relay apparatuscontrolled'by the primary movable member and operating periodically torebalance the measuring circuit, control and operate the indicating andrecording unit assembly. 'I'he apparatus includes also a recalibratingmechanism operated by the drivingelement effective periodically torecalibrate the measuring circuit to compensate for variations in anyelectrical condition of the source of power for the measuring circuit,and means for synchronizing, and accurately controlling the phaserelationship between, the mechanical relay apparatus and therecalibrating mechanism.

In case'this invention is applied to a printing recorder, as contrastedto a continuous curve drawing recorder, the marker or printing elementor assembly is operated by the driving element and is interlocked withthe calibrating operating mechanism to prevent operation of the markerduring a recalibrating cycle; and there is provided also means forsynchronizing, and accurately determining the phase relation between,the marker operating mechanism and the mechanical relay apparatus. Incase this invention is applied to a multiple-record indicating,recording or measuring apparatus; that is, ap- "paratus for measuring aplurality of similar or different conditions at the same or differentpoints or locations, it includes also means rendered inoperative duringa recalibrating cycle, for successively advancing the marking element orassembly, preferably in step-by-step motion, and for simultaneouslychanging the circuit connections of the measuring circuit successivelytorespond to a plurality of predetermined conditions in a definitesequence, and the apparatus includes also mechanism for synchronizing,and accurately determining the phase relation between, the operatingmechanism for advancing the marking element and operating the circuitcontroller and the mechanical relay apparatus.

This invention comprises also improved and simplified sub combinationsor component mechanisms of a combined indicating, recording and/ormeasuring apparatus of the type Just described by means of which a highdegree of accuracy and reliability of operation is attained.

A further feature of this invention comprises an improved recordingelement assembly particularly suitable for use in the combined apparatusdescribed above, and also an improved universal single or multiple pointrecorder element assembly, and to new and improved inking devicesparticularly useful in connection with such recorder element assembly.

The term "measure is used herein to connote any indication, recording,controlling or other eifect which is derived from and constitutes ameasure of a given primary condition.

For a better understanding of this invention, together with other andfurther features thereof, reference is had to the following descriptiontaken in connection with the accompanying drawings, and its scope willbe pointed out in the appended claims.

In the drawings,-1"ig. l is a view in rear elevation, of a combinedindicating-recording apparatus embodying our invention;

Fig. 2 is a front elevation, partly broken away, of the apparatus ofFig. 1;

Fig. 3 is a top plan view of the apparatus of Fig. l; a M

Fig. 4 is a cross-sectionalview of the recorder element assembly shownin lfigs. 1 through 3;

Fig. 7a is a detail of an operating cam of the mechanism of Fig. 7;

Fig. 8 is a schematic circuit diagram of a measuring circuit and itsassociated elements with elements corresponding to those shown in thepreceding figures identified by like reference characters. A

Fig. 9 is a cross-sectional view of the current calibrating operatingmechanism along the lines 99 of Fig. 3; 7

Figs. 10 and 11 are, respectively, front and side elevations of amodified form of inking device;

Fig. 12 is an exploded perspective view of selected parts of themechanism of Figs. 1-9, particularly the calibrating mechanism, theprinting mechanism, and associated drive shafts, timing gears andoperating cams;

Fig. 12A is a side elevation of one of the discs of Fig. 12 togetherwith a part of its associated follower;

Fig. 13 is a perspective view of a modified form of mechanism suitablefor the control of the printing or recording mechanism; and

Fig. 13A is a fragmentary end elevation of Fig. 13. v

It is believed a clear understanding of the arrangement and operation ofthe various parts of the apparatus will be best understood from acomplete description of the operation of the apparatus as a whole, andtherefore the construction and arrangement of certain of the mechanismsor component parts of the apparatus by themselves will befirst'described in detail.

Referring now more particularly to Figs. 1, 2,

I and 3 of the drawings, there is shown one embodiment of this inventioncomprising indicating, recording and/or controlling apparatus operablein response to changes or variations inimagnitude of any desiredcondition as indicated by a galvanometer G, provided with a pointer ordefleeting element Ill. The several indicating, recording and/orcontrolling elements or mechanisms to be described hereinafter may beoperated in accordance with deflections of the pointer l through anysuitable mechanical relay apparatus, although there has beenillustrated, by way of example, a particular mechanical relay apparatus,similar to that described and claimed in U. S. Letters Patent No.1,935,732, granted November 21, 1933, upon the application of L. Y.Squibb.

In brief, the mechanical relay apparatus comprises a pairlof clampingmembers or bars ll between which the pointer ID of the galvanometer Gnormally freely deflects. One of the members II is periodically movedtoward engagement with each other, and with the pointer ID by means oflinkage elements (not shown) and a cam l2 continuously rotated by apower shaft l3 driven by a motor M through a worm l4 and a worm wheel M.There are also provided a pair of scissors-like pointer engaging arms orfeelers l5 pivoted respectively at l5a on a plate 9 (shown in dottedoutline for the sake of clarity) and biased into engagement with eachother by a suitable spring 16. The plate 9 is pivoted at its upper endfrom the frame of the apparatus and about an axis parallel to the planeof the paper, as viewed in Fig. 1. Secured to the arms l5 are the camfollowers lib, which ride on the cam surfaces l2b of the cam element I2,the arms being thereby separated to disengage the pointer 10 for apredetermined portion of each rotation .of the shaft l3.

Also pivoted on the plate 9 at 11a is a clutch arm I! having a pin llbadjustably securedin a slot of an upstanding arm He. The pin "b isdisposed between the lower portions of the arms or feelers l5 and isadapted to be engaged thereby when the scissors are closed by thebiasing spring l6 after release by the cam l2. The outer ends of theclutch arm I! are provided with clutch surfaces or shoes (not shown)cooperating with a clutch rim l8a of a clutch disc l8. The outer ends ofthe clutch arm II are provvided also with cam surfaces or followers llddisposed in the path of rotation of a pair of cams l9, driven by theshaft I3. The clutch disc I8 is rigidly secured to a shaft 20 (Figs. 2,3) journaled in the frame of the apparatus The manner in which the abovedescribed apparatus operates periodically to rotate the shaft 20 throughan angle dependent upon and constituting a measure of the deflection ofthe pointer III of the galvanometer G is set forth in detail in theabove entitled Squibb patent. In brief, assuming the parts to occupy thepositions indicated in Fig. 1, the galvanometer pointer I0 is free todeflect in response to variations in magnitude of the condition to bemeasured or controlled. At a predetermined point in a cycle of rotationof the shaft I3, as determined by the cam 12, the pointer III in itsdeflected position is clamped between the bars ll. Substantiallyimmediately upon the clamping of the pointer I by the bars II, the camfollowers lib ride oil! the cam surfaces 12b and release the arms orfeelers l5, which move toward engagement with each other under theinfluence of the biasing spring l6. In case the pointer III haspreviously been deflected in response to a change in magnitude of thecondition to be measured, one of the feelers IE will engage the pointerbefore the other, which latter then moves beyond its central or neutralposition until it deflects the clutch arm I! an amount corresponding tothe deflection of pointer l0. More specifically, the plate 8, prior torelease of the feelers, has been moved by the cam l2 about its pivot todisengage the clutch arm II from the clutch disc l8 so that the arm I!is free to move. The lower arm of that one of the feelers l5, which hasmoved beyond its neutral position as aforesaid, engages the pin I lbsecured to the arm l1, and rotates it, about its pivot l'la through anangle proportional to the deflection of the pointer l0; thereafter thecam l2 releases the plate 9 and the arm I! in its new position isreturned into drivlng engagement with the clutch disc I 8a. One ofrotating cams I 9 then engages its associated cam follower "d, which hasbeen deflected upwardly into its path of rotation by angular movement ofarm l1, and; during continued rotation of the cam, returns the clutcharm I! to its normal or horizontal position, at the same time drivingthe clutch disc ll through an equal angle.

The clutch disc I8 is secured to a shaft 20 journaled in the frame ofthe apparatus, the angular movement of the shaft being utilized to drivethe indicating, recording and/or controlling elements of the apparatus.For example, an insulating disc 2|, Fig. 2, secured to the shaft 20 maycarry a potentiometer Mil cooperating with a stationary adjustablecontact 2). and this 'slidewire or potentiometer may-preferably be inapulley 22 cooperating with a cord or endless belt 23, Fig. l, passingover idler pulleys 25 and attached by screw clamps 25b to a carriage 25carrying the indicating and recording elements. As shown more clearlyin-Figs. 4, 6, 7, 12, and 13, the carriage" comprises asubstantiallyboxlike frame, open at top and bottom, and suitablyfabricated from sheet metal. Disposed within the carriage-frame 25 is adriving gear 25 secured on a sleeve 21 journaled in the ends of theframe 25. The respective ends of the sleeve 21 are of reduced diameterand pass respectively through corresponding openings in the ends of theframe 25, Figs. 3, 5, and 12, the shoulders 21s bearing against theinner sides of the ends of the frame to insure lateral movement of thesleeve 21 and carriage as a unit and to permit rotation of gear 25independently of the carriage 25. A driving connection between thesleeve 21 and shaft 28 is provided by a longitudinal slot or keyway 23ain which is disposed a key interconnecting the shaft and the sleeve 21.As shown more clearly in Fig. 5, a cylindrical key 21a is secured withinthe sleeve 21 by a set screw 21b, the key 21a sliding with minimumfriction in the slot 28a of the shaft 23. Projecting from the carriage25 are a pair of arms 25a which slidably engage a guide shaft or rod 23to prevent rotation of the carriage 25 about the shaft 23.

A second box like frame, Fig. 6, having upstanding ears or lugs 30a ispivotally. supported from the frame 25 by means of pivot pins 30!)passing through apertures of the frame 25 and the upstanding lugs 30a.Journaled between the side bars of the frame 30 and extending at rightangles to shaft 23 is a shaft 3| upon which is secured a helical drivengear 33, Fig. 4, meshing with driving gear 25 substantially in a linepassing through the axis of the pivots 33b. Also secured to the shaft 3|is a recorder device or printwheel 32 provided with a plurality ofprinting characters or like marking elements, and an index plate 34.From the front end of the frame 33 or, as viewed in Figs. 4, 5, and 'l,at the left end thereof, there extends a U-shaped member, one arm 35 ofwhich constitutes an indicator which cooperates with a stationary scale36. Depending from the carriage-frame 25 is a V-shaped plate or arm 31(Figs. 1, 4, 6, and '7) having a pin 38 in its lower extremity disposedto engage peripheral recesses in the index plate 34, as described morefully hereinafter.

A second V-shaped plate or bracket 33 extends upwardly from the forwardside bar of the frame 25 and may be integral therewith or, asillustrated in Fig. 4, may be adjustably secured by a screw or nut andbolt 40 passing through a slot in the bar of the frame 25 and a hole inthe bracket 33, or vice versa. The bracket 39 preferably extendsupwardly at an angle of approximately and journaled therein is a stubshaft 4| upon which is secured a helical gear 42 also meshing with thedriving gear 26. A second stub shaft 43 is provided with a threadedextension 53a engaging a threaded recess in the shaft ll and forms anextension thereof. The shaft 43 is provided with a knurled end 4317 tofacilitate engagement and disengagement between the shafts II and 43. a

' preferably proportioned to fit closely within the recesses a and aretaining dmc or plate 45 is secured to the face of the disc 44 byscrews a additionally to retain the inking pads b in the disc 44. Theinking drum 44 is loosely- Journaled on the shaft 43 and, in order tosecure proper synchronization between the drum 44 and the printwheel 32,an arm 45 is secured'to and projects from the stub shaft ll and engagesin a recess c of the drum 44 forming a driving engagement therewith.

In order to tilt or oscillate the frame 30, in which is mounted theprintwheel 32, to bring the latter into engagement with the recordchart, the frame 30 is provided with an extension or arm 30c terminatingina cylindrical guide element 30d disposed in a key'or slot 230 in theshaft 23. Movement of the shaft 29 in a clockwise direction (Fig. 4)thereby tilts the frame 30 and the printwheel 32 until the latterengages and registers a distinctive character upon the record chart.

In certain instances, as for example, when the printwheel 32 is providedwith a plurality of distinctive record characters, a single color inkingpad sufflces. In Fig. 6 is shown a modified assembly in which thebracket 39, of Fig. 4, supporting the inking pad drum 44 is replaced bya bracket 41. The bracket 41 terminates in a holder "a in which ismounted an ink pad 41b registering and cooperating with the severalrecord characters of the printwheel 32. The bracket 41 is secured to theframe 25 by suitable screws or bolts 4|! and is preferablyinterchangeable with the bracket 39, so that either may be replaced bythe other simply by releasing the screws or bolts 40.

The printwheel 32 may register its record upon any suitable record chartdriven by any wellknown mechanism. By way of example only, there isshown (Figs. 1, 2, 3, and 7) a continuous strip chart which, as suppliedfrom a feed roll (not shown), passes over a chart drum or driving roll5| and thence over a backing plate 52, during which passage the recordmay be viewed by an observer. By mounting the printwheel 32 with itsaxis normal to the face of the chart and arranging the characters alonga beveled edge thereof the printed record is visible from the front ofthe instrument as soon as the printwheel is returned to its normalposition as shown in Fig. 2 and described with greater particularityhereinafter. Mounted on the main power shaft I3 is a worm 53 (Fig. '7)engaging a worm wheel 54 mounted upon and driving a shaft 55 which,through gearing 56, drives a shaft 51 on which is secured a worm 58registering with a worm wheel 53 secured to the shaft 60 of the chartdrum 5!. Consequently the chart 50 is continuously driven at low speedfrom the power shaft l3.

While the printwheel 32 may be advanced stepby-step by any well-knownmechanism to bring in succession its characters into printing positions,it is advantageous to use in accordance with the present invention amechanism which not only advances the printwheel but also servesperiodically to oscillate or tilt the printwheel 32 into momentaryengagement or registration with and a double -armed member or bell crank62 independently movable with respect to but journaled on the shaft 28and on one arm of which is pivotally mounted a ratchet pawl 88 biasedinto engagement with the wheel Si by means of a spring 88a. There isalso provided a locking ratchet pawl 84 mounted on a stationary pivotand biased into engagement with the ratchet wheel Si by a spring 84a,thereby preventing reverse rotation of the ratchet wheel 8i. Referringto Fig. 7, the other arm of the bell crank 82 is provided with a slot620. in which slides a pin 68 adjustably secured in a slot 86a of onearm of a second bell crank 88. The other arm of the bell crank 88 isoperated'by a mechanism comprising a link 81 and an arm-88 pivotedintermediate its ends on a fixed pivot pin 88a. The link 81 is connectedto the end of the arm of the bell crank 88 by a pivot pin 8111, while inits other end is provided a slot 81b in which is adiustably secured apin 88 journaled in the end of the arm 88. A biasing spring Iii attachedto the upper portion of the arm 88 tends to rotate it in acounter-clockwise direction, thus moving the bell crank 82 also in acounter-clockwise direction to advance the ratchet pawl 88 with respectto ratchet wheel 8i so that, upon subsequent return of the operatingmechanism to the position shown in Fig. 7, the ratchet wheel 8i will beadvanced through a predetermined angle or step. An adjustable stop ii isprovided to limit the throw of the operating arm 68 under the influenceof the spring 10.

The operating mechanism above described is normally restrained in aposition shown in Fig. 7 by means of a cam follower, shown as aprojection or pin 12 (Fig. 12) extending from the lower arm of themember 88 and riding on the face of a cam or disc 13 provided with asingle peripheral notch or recess 13a (Figs. 1, 2, and 7a). The disc '13is driven by a worm wheel I4 engaging the worm 58 driven by the mainpower shaft i3. Therefore, once each predetermined number of revolutionsof the shaft ii, the pin 12 registers with the recess 13a, permittingthe arm 88 to move in a counter-clockwise direction under the influenceof the spring iii.

It is highly desirable that the print wheel 82 shall be prevented fromregistering with the record chart" during that portion of the cycle inwhich the clutch arm il (Fig. 1) engages the clutch disc i8, since arotation of the disc l8 might produce a transverse movement of theprintwheel carriage during the printing operation and smear or blur therecord chart. The timing of the registration of the printwheel 32 withthe record chart 5i with respect to the cycle of operation of themechanical relay apparatus described above is obtained by means of a camI8 (Fig. 7) mounted on the shaft i8 and provided with a single recess160 with which cooperates a projection or pin 15 (Fig. 3) adjustablysecured in the lower end of the arm 68. It is clear that the cam 18operates at a speed of a lower order of magnitude than that of the cam18. Thus, the pin 12 and the disc 13 determine the frequency ofregistration of the printwheel 82 with the record chart II, asdetermined by the gear ratio between the worm 88 and worm wheel 18,while the pin 18 and the cam 16 accurately time or phase theregistration of-the print wheel with respect to the angular position ofshaft i3 and its cam i2, or with respect to a desired portion of thecycle of operation of the mechanical relay apparatus. Both the disc 18and the cam 18 are adjustable with respect to their respective shaftsIla and II, to insure proper phasing with respect to the mechanicalrelay.

It is often desirable automatically to switch the circuit of thegalvanometer G between several measuring circuits simultaneously withthe suc cessive step-by-step movement of the printwheel 82 and theinking drum 88. To this end, the shaft 28 which imparts the step-by-stepmovement to the printwheel 22 and the inking drum 44 carries a gear 'i'iwhich, through an intermediate idling gear 18, drives a gear 19 attachedto a shaft 80. Upon the shaft (Fig. 1) is mounted a bevel gear 8icooperating with a sec ond bevel gear 82 secured on the shaft 83, on thelower end of which is attached a rotatable brush member 84. The member84 cooperates with the stationary member 85 carrying a plurality ofsegmental annular contact members 85a. The selector switch comprisingmembers 84 and 85 is preferably enclosed within a casing 81 which maycontain oil or other suitable lubricating medium.

The operation of the above described automatic multiple-recordindicating and recording apparatus will be understood more clearly bynow referring to Fig. 8 in which is shown a schematic diagram of asystem, including certain of the several elements thus far described,for successively measuring the magnitudes of a plurality of conditionsat the same or different locations, for example, the temperatures at aplurality of points or locations; in one specific example which hasoperated satisfactorily, 16 points. Thus, by multiple-point recordingand/or indicating means, reference is made to provisions for utilizingthe same instrumentality for successively measuring and/or recordingconditions as measured at a plurality of points by condition-responsivemeans individual to each point or location. In Fig. 8 it is seen thatthe measuring circuit includes a potentiometer comprising a slidewire oradjustable resistance 2ia having an adjustable contact 2 I b connectedin series with fixed resistors 81a and 88 and energized from a source ofcurrent, such as a battery 89, through a callbrating resistance 90provided with an adjustable contact 90a. The galvanometer G is connectedin circuit successively with one of several thermocouples 92 or otherprimary condition-responsive elements through a two-position switch 9i,when in its left-hand position, as seen in Fig. 8, and in series withthat portion of the potentiometer 81a'-2ia88 comprising the resistance81a and the left-hand portion of the slidewire 2 la.

It is now believed that a comprehensive understanding of the invention,including the construction; arrangement and operation of the apparatus,will be facilitated by a description of the operation of theorganization as a whole. To this end it will be assumed that the movableelement of the selector switch has just been moved to the position shownin Fig. 8 of the drawings, in which it completes the circuit through oneof the several thermocouples 92. If the temperature as measured by theparticular thermocouple 92 is different from that indicated by thepreceding thermocouple and with which the setting of the adjustablecontact 2i b of the slidewire 2ia corresponds, an unbalance voltage willappear in the circuit of the galvanometer G which will deflect itspointer i0. When the pointer i0 is thus deflected, a motion will beimparted to the shaft 20, Figs. 2 and 3, carrying the slidewire 2iawhich, within predetermined limits, is representive of,

wire 2 a will be moved in a sense which will tend to rebalance themeasuring circuit of Fig. 8.

In case the initial movement of slidewire 2l'a is insuflicient orover-suflicient to rebalance the measuring network, the mechanical relayapparatus repeats its cycle of operation again to adjust thepotentiometer slidewire 2|a to rebalance the measuring circuit. Therelay apparatus, before printing, may operate for a predetermined numberof revolutions of the shaft I3, such as 24, which is suificient toinsure a complete balancing of the measuring circuit of Fig. 8

even under extreme changes in electromotive force between successivethermocouples occasioned by widely varying temperatures at the difierentmeasuring points.

Simultaneously with movement of the slidewire 2|a the carriage andassociated elements are, by the driving pulley 22 and the endless belt23, moved across the chart 5|. The position of 25 the indicator 35 withreference to the scale 36 (Fig. 2) is a measure of the magnitude of thecondition under measurement. As .soon as the potentiometer circuit isrebalanced a direct reading may be taken which will correspond with 3great precision to the magnitude of the condition under measurement.

After a predetermined number of cycles of operaticn of the mechanicalrelayapparatus, corresponding to the number of rotations of shaft I3 35as determined by the ratio of the worm 53 and the 40 or recess 13a ofthe disc preparatory to the printing or recording operation.

Just prior to registration of recess 13a and pin 12, an effective inkingof the uppermost marking element of the printing wheel 32 is 45accomplished by means of a raised or punched out portion 13b (Figs. 7aand 12A) corresponding with the leading end of the notch or recess 13aof the disc I3. Thus as the raised portion 13b is moved into engagementwith the pin 12, a

50 slight clockwise movement is imparted to the arm 68 which movement istransmitted through link 61, bell crank 66, shaft 29 and extension 330to rotate the uppermost character of print wheel 32 into firm engagementwith the corresponding 55 one of the inking pads 44b carried by the disc44. A slight-additional movement of the disc 13 releases arm 68 whichthen moves through a sinall angle in a counterclockwise direction to itsoriginal position. By this means an effective 60 inking of the severalmarking elements of the disc or print wheel 32 is accomplished, at thesame time avoiding the continuous pressure between the print wheel 32and the disc 44 which "would result in increased friction or possible 65binding of the elements of the recorder assembly.

As stated above, for the printing operation the release of the operatingarm 58 is accurately timed, with reference to the operating cycle of therelay mechanism, by the cam I6 and the aux- 0 iliary pin 15. Thus,immediately after the cam 12 disengages the clutch arm l1 from the discl3 the cam 16 is arranged to move its recess 16a into registration withthe pin 15 carried by the arm 88. This arm is thereby released for 15movement in a counter-clockwise direction under the influence of theoperating spring ll. As the arm 53 moves, the pins or followers 12 andI5 respectively enter recesses 13a and 16a and thebell crank 66, nowrotated by operating arm 58 and link 51 in a clockwise direction,drives, in a clockwise direction, the shaft 23 which in turn moves theprint wheel supporting frame pivoted at 30b through a correspondingangle in a counter-clockwise direction, the movement being suilicient toinsure registration of the print wheel 32 with the record chart 5|. Theduration of the time the print wheel 32 is in engagement with the chart5| is determined by the size or extent of the recess 15a of the cam I6.Since the chart is continuously driven from the main shaft I3 the recess16a has a configuration such that the print wheel 32 moves rapidly intoand out of engagement with the chart thereby to prevent blurring orsmearing and to insure a single imprint of the record mark or indicia bythe print wheel 32 upon the record chart.

It may here be observed that the axis of the print wheel 32 is normal tothe plane of the face of the chart 5| (Fig. 2) and that during theprinting operation the print wheel or disc 32 registers with the chartforwardly and substantially below the top of the chart drum. Inconsequence, as soon as the print wheel 32 is returned to its normalposition and out of engagement with the chart 5|, the record leftthereon is immediately and readily visible from the front of theapparatus, as shown in Fig. 2.

Simultaneously with the printing operation, the bell crank 62, is byclockwise movement of bell crank 66 rotated in a counter-clockwisedirection, the ratchet orpawl 63 merely sliding over one tooth of theratchet wheel 6|, which is locked against rotation in this direction bythe locking ratchet pawl 64. However. as the arm 58 is returned to theposition shown in Fig. 7 by the cam 16 operating on the pin 15, theshaft 29 is again rotated to the position shown in Fig. '7, returningthe print wheel 32 to its normal position. During this return motion,the bell crank 62 is rotated in a clockwise direction and drives theshaft 28 through a similar angle by means of the ratchet pawl 63. Thisrotation of the shaft 28 is adjusted by means of the adjustable pins 55and 69 to correspond exactly to the angle between adjacent recordcharacters or marking elements on the periphery of the print wheel 32.The shaft 28 through the helical gears 26, 33 and 42 drives the printwheel 32 and the inking drum 44 through corresponding angles, so thatthe print wheel 32 is in position to register the condition at asucceeding location or point under measurement in response to a changein circuit connections as is presently to be described.

As mentioned above, the spiral gear 33 meshes with spiral gear 26 on thepivotal axis through screws 30!). This is done in order to preventrotation of the print wheel upon its movement into engagement with thechart.

In order substantially to eliminate errors in the registration of theprint wheel 32 on the record chart 5|, due to any lost motion in thedriving mechanism between the shaft l3 and the print wheel 32, an indexplate 34 is carried by the same shaft as the print wheel 32 and isrigidly secured thereto. This index plate 34, upon depression of theprint wheel 32 as described above, engages a projecting pin 38 on thedepending stirrup or bracket 31 secured to the frame 25 of theindicating and recording element assembly, and guides the print wheelduring printing.

The peripheral notches or indentations of the index plate 84 are inexact angular alignment with the record characters or printing elementsof the print wheel 82 so that the angular position of the print wheel 82is accurately determined for each printing registration, therebyinsuring that each character is moved flat against the chart III. Afurther important function is to prevent rotation of the print wheel 82and to prevent lateral displacement of the record which might otherwiseresult. In this manner, all records are accurate to within one-quarterof a per cent and no inaccuracies are introduced by lateral displacementof the printed record.

In brief then, the galvanometer G is automatically and successivelyconnected in circuit with the several thermocouples 82 and, after eachsuch number of cycles of operation of the mechanical relay apparatussufficient to insure the rebalancing of the measuring circuit, therecording mechanism, which has been moved to a new position with respectto the chart, is automatically operated to register an indication on therecord chart of the magnitude of the condition existing at theparticular point under measurement and the indicator 85 indicates thisvalue on the cooperating scale 88. Thereafter, the galvanometer issuccessively connected in circuit with the other thermocouples and theabove described cycle of operation is repeated; For each point, theindicator and recorder element assembly is moved transversely of thescale 88 (Figs. 2, 3. 4, 6, and 7) and the record chart 58, so that theindicator 85 will indicate on the scale 88 the magnitude of thecondition existing at the point of the measurement; this magnitude maybe registered on the record chart graduated as the scale 88 by means ofthe impression left by print wheel 82. At the same time a numeral 82a onthe front face of the print wheel 82, appearing through the opening inthemask 821), indicates the number of the control point at which themeasurement is being taken. Preferably a corresponding numeral isprinted on the chart by the print wheel 82..

It will be noted also that the connection of the galvanometersuccessively into the several thermocouple circuits is automaticallysynchronized with the step-by-step movement of the print wheel 82 andthe inking drum 44 through the gearing TI'I8'I8-8I--82, described above.

It is well understood that the voltage of a battery, such, for example,as that utilized to energize the potentiometer measuring circuit of Fig.8, varies appreciably with time, and that the accuracy of measurement,as determined by the above described apparatus, depends upon theconstancy of current to the slidewire 2Ia; that is, the constancy of theterminal voltage of the battery 88. In order to compensate forvariations in voltage of such a battery, it is desirable periodically torecalibrate or restandardize the measuring circuit by substitutingtherein a standard electrical unit, preferably an auxiliary standardcell or source developing a constant or standard electromotivei'orce.For example, referring to Fig. 8, if the switch 8| be operated to itsright-hand position, the galvanometer G will be connected directlyacross the potentiometer circuit in series with a standard cell 8supplying such an electromotive force. Under normal conditions, thevoltage of the standard cell 8 just balances that across thepotentiometer comprising the resistances 81a and 88 and the slidewire2Ia. If, however, the voltage of the battery 88 has changed, themeasuring circuit will no longer be balanced. It may be restored tobalance by varying any desired electrical condition or constant of themeasuring circuit, for example, by adjusting the contact 88a of thecalibrating resistance 88.

It is desirable to effect this restandardization or recalibrationautomatically and periodically, for example, every half orthree-quarters of an hour, corresponding to a predetermined highernumber of revolutions of shaft I8. To this end, there is provided an arm88 (Figs. 1-3 and 12) pivotally supported at 83a, and periodically released to operate, through the auxiliary pivoted arm 84 and projection8411, the switch 8i above described in connection with Fig. 8. 'Thus,depression or clockwise rotation of the projection or element 84a, Figs.1 and 12, corresponds to a movement of the switch 8I of Fig. 8 to itsrighthand position.

The time between successive operations of the arm 88 and of the switch8I is determined by means of an adjustable rotating cam or disc 85,having a single peripheral notch or recess 85a, driven from the shaft I3through an intermediate double-worm gear reduction drive. The gearratio. provided by the aforesaid drive and comprising worm 88 secured toshaft I8, and driving worm wheel 81 on shaft 81b which in turn drivesthrough its associated worm 88a and worm wheel 88 the disc 85, is veryhigh, for example, of the order of 1200 to 1; that is, for twelvehundred revolutions of the shaft I8 the disc 85 completes onerevolution. During that revolution the peripheral notch 85a is movedinto registration with the projection or cam follower 88b of the arm 88which is biased for clockwise rotation, as by a spring 83c.

Immediate movement of the arm 83, however, is prevented until the recessI Illa of an adjustable cam MI is moved into registration with anadjustable cam follower or pin I82, Figs. 9 and 12, carried by the arm88. The delayed movement of arm 88 is for the purpose of preventingoperation of the switch 8I until the galvanometer needle or pointer I IIis clamped between the bars II, Fig. 1. To this end, the angularposition of the cam IIII is predetermined with respect to the shaft I 8and its cam I2, so that after registration of notch 85a with projection83b, registration of recess Illa with pin I82 occurs substantiallyconcurrently with, or immediately after, the clamping of pointer III.This phasing or timing is readily accomplished by proper angularadjustment of the shaft 81b and the cam IIII provided for by a splitcollar 81a, Fig. 3, of worm wheel 81. In consequence, violent swingingor deflection of the galvanometer pointer I II incident to the openingand closing of switch 8| is prevented. Thus the cam 85 and projection88b determine the frequency of recalibration as determined by the gearratio of the double-worm drive, while the cam IIII, operating at asubstantially higher speed than cam 85, and the projection I82accurately phase or time the operation of the switch 8| with theaforesaid desired portion of the cycle of operation of the mechanicalrelay mechanism.

Assuming now that the'galvanometer needle III is clamped into a fixedposition by the bars II and that disc 85 and cam IIII occupy positionsfor recalibration, the arm 99, under the influence of the relativelystrong spring 93c. rotates about its pivot 99a in a clockwise direction,rotating with it the arm 94 whose projection 94a operates the switch 9|to establish the recalibration circuitconnections. The aforesaidclockwise rotation of arm 94 increases the tension in a return spring94!) connected to that arm and to a flxed support as well as the tensionin a spring 99b which interconnects one end of an arm 99 and a dependingprojection 94d of the arm 94. Obviously, the main operating spring 990is powerful enough to overcome the opposition offered by springs 94b and99b to movement of arm 93.

The biasing force developed by the spring 9917 however tends to rotatethe arm 99, pivoted for independent movement on the shaft 91b, in aclockwise direction thereby to move a clutch disc I99 pivotallysupported at I99a on the lower end of the arm 99 into driving engagementwith the rim or flange 22a of the pulley 22. Supported on the frictiondisc I99 is the calibrating resistance 99 shown in Figs. 2 and 12 in theform of a slidewire and automatically adjustable to compensate fordeviation from a predetermined value of the voltage of the battery orsource of supply 99.

Since, as described above, the switch 9| is operated at the time thepointer I9 is clamped, it is undesirable to operate the friction discI99 into driving engagement with the pulley 22 until later in the cycleof operation of the mechanical relay; that is, until after the feelersl5, Fig. l, have set the clutch arm I! to correspond with thegalvanometer deflection and the cams I 9 have thereafter returned theclutch arm I! to its horizontal or neutral position. Therefore,immediately prior to operation of the switch 9| by arms 93 and 94, a camI93, adjustably carried on, and driven by the shaft 91b in predeterminedphase relation with respect to shaft I3 and its cam I2, and retarded inphase with respect to cam I9I, moves its pointed projection I93a againstone end of an arm I94 pivoted intermediate its ends on the frame at Ma.The opposite end of the arm I94 cooperates with the arm 99 to preventmovement thereof, by means of a slot I94?) engaging a pin 99c projectingfrom the rear of the arm 99 as viewed in Fig. 2 but shown on the frontof the arm for convenience in Fig. 12. The pointed projection I93a is byshaft 972) moved clear of the lever I99 immediately after the return ofthe clutch bar I1 to-its horizontal position. The spring 99b is theneffective to rotate the arm 99 until the aforesaid driving connectionbetween clutch disc I99 and pulley 22 is effected.

The calibrating mechanism is now in readiness for recalibration of themeasuring system, as the potentiometer circuit of Fig. 8. Since therecalibration of the potentiometer circuit occurs at predetermined timeintervals, as determined by the aforesaid double-worm gear drive, andindependently of the position of the selector switch 85 or of theprinting and/or recording mechanism, successive calibrations may takeplace with the selector switch in different positions.

Therefore, suitable mechanism is provided to prevent operation of theselector switch 9495 and the printing and/or recording mechanism duringthe operations constituting the recalibrating cycle. In one form of ourinvention, this mechanism comprises a disc I91 adjustably supported on aworm wheel I95 by means of screws I9'Ibdriven by a worm I96 secured tothe shaft 140, a projection I9Ia on the disc I91 cooperatprojectionI'9Im of the disc I97 and the notch 99a of the disc 9!, taken inconjunction with their respective gear ratios from the main shaft I3, ispredetermined so that the projection I9la is always moved below or inthe path of stop element 99b after notch 99a registers with projection93b and. before the cam I9 and disc I9 occupy positions for printingand/or recording operations. Therefore, even though the arm 99 is, bydisc I9 and cam 19, freed for actuation of the switch 94--95 and theprinting and/or recording mechanism, such operation cannot occur untilthe projection I9Ia moves out of engagement with stop element 991) atwhich time recalibration has been completed.

Continuing with the. operation of the recallbrating mechanism, shortlyafter the clamping of the pointer I9 and the deflection of the clutchbar II, the feelers I5 by cam I2 are spread and one of the clamping barsII operated to release the pointer for deflection. The galvanometerpointer then deflects in accordance withany unbalance which may existdue to change in the voltage of battery 99. During the time the needleor pointer I9 is moving to its new position, the clutch arm I I isreturned to its neutral or horizontal position and the aforesaid drivingconnection completed between the rim 22a secured to pulley 22 and thefriction disc I99. Thereafter the needle is clamped by bars II in itsnew position, the feelers again move the clutch arm to an angularposition corresponding to the degree of deflection of the galvanometerpointer from its neutral position. The restoring cams I9, after arm I!again engages the clutch disc I9, return arm I! to its horizontalposition. In this case the corresponding angular movement of arm IT andclutch disc I9 is by shaft 29 and rim 22a transmitted to the frictiondisc I99 which moves the slidewire 99 to a new position. The directionof movement of the slidewire is, as referred to the circuit of Fig. 8,in the direction to correct for the extent of deviation in the voltageof battery 89 from its predetermined value.

The foregoing cycle of operations is repeated several times, eightcycles being safely suflicient, to insure that the slidewire 99 is movedaccurately and with great precision to a position where thepotentiometer voltages as derived from the battery 99 and the standardcell S are in ex act balance. The number of cycles of operation,preferably about eight,- is determined by the shape and extent of therecess I9Ia and its speed as compared to that of the shaft I3. Thusafter the shaft I3 has completed eight revolutions, corresponding to theaforesaid eight cycles of operation, the cam I9I occupies a position toinitiate counter-clockwise rotation of arm 93. Additional rotation ofthe cam I9I raises the pin or projection I92 from recess I9la therebyreturning the arm 93, against the bias of the main spring 930, to itsoriginal position. The arm 94, under influence of the spring 94b, moveswith or follows after the arm 93 to release the switch 9I- which isautomatically returned to the position shown in Fig. 8, as by resilientmembers upon which the switch contacts are mounted. In addition topredetermining the number of cycles for recalibrating the circuit, thetrailing operating surface of the cam IN is phased or angularly disposedwith respect to shaft I9 and cam I2 so that the return ofthepotentiometer system to one of elements 92 occurs during that portion ofthe mechanicalrelay cycle when the galvanometer pointer is clamped in afixed position.

The driving connection between the recalibrating slidewire 90 and therim 22a is broken by reason of the engagement of arm 94 with theadjustable set screw 99d carried by arm 99. Thus as arms 94 and 99 arerotated in a counter-clockwise direction by the spring 94b, the frictiondisc I and slidewire 90 are returned to their original positions, Figs.2 and 12.

-The three-part calibrating mechanism comprising arms 93, 94, and 99together with their associated biasing springs and pivotal mountings isparticularly well adapted for the purposes and functions describedabove.

As explained above, the voltage of the battery 89, with use and over aperiod of time, gradually decreases in value so that the slidewire 90during a relatively long period, which may be of the order of sixmonths, will be substantially entirely excluded from the potentiometercircuit. To show the position of the slidewire and generally to indicatethe condition of the battery, an index 99f may project from a portion ofthe frame, or as illustrated, Fig. 2, from the arm or lever 99 and' maycooperate with graduations or an arrow I 0022 marked on the disc Hill.In any event, when the arrow and index are substantially in alignment,all of the slidewire 99 has been excluded from the circuit indicatingthat no further correction for decreased voltage may be accomplished bythe slidewire 90. For continued accuracy a new or re-charged batterymust then be included in the circuit, or the supply voltage as appliedto the measuring circuit otherwise increased. 1

Continuing with the operation of the apparatus, the projection lil'la ofdisc I01 frees the arm 68 after the galvanometer is again connected incircuit with one of the condition responsive elements 92 and before thecam or disc 13 and cam- 16 again occupy positions for the printingand/or recording operations. In addition to being phased with respect todisc 95 and cam lill, the projection lll'la, by reason of its angularposition and the gear ratio between worm I08 and worm wheel I05, ismoved out of registration with stop element 68b after the recess 13a ofdisc I3 moves beyond projection 12. In this manner the first printingand/or recording operation subsequent to recalibration occurs aftersubstantially the full number of cycles of operation of the mechanicalrelay, thereby insuring the rebalance of the circuit before printing;that is, recalibration requires eight cycles of operation; twenty-fourcycyles are provided between each printing operation. Thus afterrecalibration the mechanical relay apparatus operates at least sixteentimes to insure accurate indication of the magnitude of the conditionunder measurement. It may here be observed that unbalance of the circuit(Fig. 8) during recalibration is independent of the position ofslidewire Ila. Consequently the carriage 25 and frame 30 are moved but aslight amount during recalibration. Moreover, since the switch 84-85 isretained in fixed position during recalibration, the galvanometer isreconnected in circuit with the particular one of elements 92 with whichit was connected just prior to initiation of the recallbrating cycle.

If the foregoing provisions were not made, a printing operation mightoccur during calibration; in that event the resulting record on thechart i would be confusing and of little value. Moreover, there would belost a record of the condition indicated by one of the elements 92.

In accordance with the present invention, however, the operation of theprinting and/or recording mechanism is interrupted until aftercompletion of the calibrating cycle and until after the mechanical relaymechanism has again rebalanced the circuit and moved the carriage 25 andprint wheel 32 to a position with respect to the chart which is anaccurate indication of the magnitude of the condition under measurement.

In one embodiment of the invention recalibration was provided for each1200 revolutions of shaft l3, or after each forty-ninth printingoperation. Thus with the sixteen control elements 92, it will be seenthat each successive recalibration cycle takes place with the selectorswitch 84-85 one position beyond its preceding position, or angularlydisplaced from the position corresponding to the precedingrec'alibrating cycle. In this manner maximum average accuracy for allpoints may be attained, particularly for a case where there is ameasurable drift in voltage of the supply between successiverecalibrating cycles.

Now that the principles of the present invention are understood, it willbe apparent the recalibrating mechanism is applicable to Wheatstonebridge circuits, in which case the slidewire 90 may be included in theratio arms of the bridge while a standard resistance or impedance deviceis by switch 9i substituted for one of the elements 92.

From the above, it is seen that there is provided a full automaticindicating, recording and/or controlling apparatus which successivelyindicates, records. and/or controls in accordance with, the conditionsmeasured at a plurality of points, and which automatically recalibratesor restandardizes the measuring circuit, at the same time avoiding anyinterference between the operations of the several component mechanisms.

In Figs. 10 and 11 is shown a modified and simplified form of inkingdevice which, in certain instances, may be used in place of the device44 of Fig. 4. This device comprises essentially a pair of spiders H0which may be integral with, or firmly secured to, a central hub adapted5o for mountlng'on the shaft 43, as in the case off j the inking device44. The several arms i Illa oi/,

the spiders H0 are provided with radial slots I illb. The spiders llllmay conveniently be formed of sheet metal so that the slotted /a'r llllahave a substantial resilience. Near "e outer end of each -of the radialslots till i is formed a notch or recess adapted to receive andresiliently retain an arbor Illa of an inking pad III which may be ofany suitable shape/t The arbors Illa and the notches in the $10 0b maybe of any suitable shape. In ca round inking pads are employed so thattheir angular relation is unimportant, the arbors Illa may be round,while the shape of the notches is unimportant. However, in case squareinking pads are employed, as shown, the arbors Ilia are preferablynon-circular and of a configuration complementary to the notches in theslots lillb; for example, as shown, the arbors Ilia may be square,fitting into V-shaped notches in the slots device'of Figsaio and v11 maybe used directly rotation. or the outer end of frame-arm in placeofinking devices similar to 44 in the recorderfelement assembly of Fig. 4.

loosely journaled on shaft 30.

In Fig. 13 there is showna modified form of ratchet mechanism which-mayreplace the cam 13, disc 13, disc -I01-and, their associated drivinggears. 'This ratchet' mechanism comprises a U- shaped frameI I5 .looselyjournaled on the shaft I II.- A" link III pivotally connected to oneframe-' arm II5aat I'II oscillates'theframe II5 under the control of acrank formed by disc I I secured 'toshaft and supporting from its face apin III pivotally engaging the opposite end of the link I I5. In orderto. phase or time the operation of the'print wheel 32 (not shown in thisfigure) a ratchet wheel I23 issecured upon a sleeve I2I, A cooperatingpawl I22, journaled on a-rod or shaft I22a secured between opposite armsof frame H5, is. biased into engagement with the ratchet wheel I20byleaf spring I22b andserves to rotate the ratchet wheel a predeterminedamount every time the shaft I3 or pin II 0 completes a revolution. Bypredetermining the position of a cam I23 carried by the sleeve I2I, itwill be apparent that for a given number of revolutions of the shaft I3the cam I23 will be rotated through 360. Thus this cam is phased, andthe ratchet mechanism adjusted, so that just prior to completion,

of the cycle of operations of the mechanical relay for a given controlpoint, a projection I23a of the cam I23 is moved against a lateralprojection I250 of a crank arm I25 pivoted from the frame at I26, andthereby rotates the crank arm I25 in a clockwise direction as viewed inFig.

13, against the bias of a spring I21, and a second spring I20, connectedto the frame and to a pin I29 eccentrically mounted on a disc I30 whichitself is secured to an operating shaft I3I. The outer or free end ofthe crank arm I25, being beneath thepin I23, is-etfective to rotate theshaft I3I in a counter-clockwise direction. Rigidly secured to shaftI3I, as by pins I32, is a rod I33 engaged by projections I34 of a frameI35, in which is journaled the print wheel 32 (not shown in Fig. 13).Accordingly, the counterclockwise rotation of shaft I3I rotates theframe I35 in a clockwise direction about pivots'30b to move the printwheel firmly into engagement with the inking disc 44.

As the pawl I22 rotates the ratchet gear I20 and cam I23 an additionaldistance, a recess I23b is moved into registration with the lateralprojection I25a. This recess may be next to the projection I230,orseparated therefrom a slight amount so that as the projection I231: ismoved beyond the projection I25a'the springs I21 and I28 are effectiveto return the respective crank arms I25 and I3I, I33 to their originalpositions, the print wheel at the same tirfie being moved out ofengagement with the inking disc 44. In any event, as soon as the recessI23b registers with the extension I250, the springs I21. and I23 areeffective to rotate respectively the crank ing operation occurs'when theframe has been moved substantially to its limit of clockwise Illb isbelow the projection I250. Accordingly, as the crank arm lll'rotatescounter-clockwise,

the projection I254 moves over the upper cam 'to the last-mentionedreturn movement of cam I23, a second cam I30 carried by sleeve I2Ioccupies a position such that its recess I35a registers with one pawlI31a of a double-pawl member I31 journaled on rod i224: and biased forclockwise rotation by springs I30. The other pawl I31b of member I31normally retained in a lifted, ineifective position, upon.-"registration of recess or notch I3 and end I31a, moves downwardlyinto engagement with one tooth of a ratchet wheel I33 secured to theshaft 80. In consequence, the shaft 00 is rotated, as the print wheel isreturned to its original position, an amount suilicient to move theselector switch 34-35 for connection of a different one of the elements32 in the potentiometer circuit. ratchet wheels, and crank H3, H8 arephased with respect to shaft I3 so that the switch movement is completedwhile the galvanometer pointer is clamped in a fixed position.

The recalibration cycles are timed and controlled by the disc 05 and camIOI in the manner described above. However, as soon as the arm 93 ismoved downwardly by the spring 530, a cam I40 journaled on shaft 50 isrotated in a counterclockwise direction by a crank journaled in theframe F, one end of which is by link I pivotally secured to arm 33 whileits opposite end is by link I42 pivotally secured to the cam I40. By theaforesaid rotation a lower end M of the cam is moved toward or againstthe projection The I25a to prevent movement thereof even though preventmovement thereof upon registration of pawl I31a with notchv or recessI360. In this manner the operating means for the,selector switch 34-45and the printing and/or recording mechanism is rendered ineffectiveduring calibration. The timing and phasing in other respects may be andpreferably is identical with r the modification of our inventionpreviously described.

While there has been described what at present is considered thepreferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madewithout departing from the invention, and therefore the appended claimscover all such changes and modifications as fall within the spirit andscope of the invention.

What is claimed is:

i. In a self-balancing measuring system including a measuring circuit, adriven member including a circuit adjusting element, a mechanical relayfor driving said adjusting element by a plurality of decreasing steps toa circuit rebalancing position and including a control elementperiodically releasedfor deflection in accordance with the sense andextent of unbalance of said circuit, relay driving means including adriving shaft, means operable by said shaft to release said controlelement and effect a stepby-step movement of said driven membercorresponding to the sense and extent of deflection of said controlmember, the combination of transfer means periodically operable aftercompletion of a predetermined low number of revolutions of said shaftfor subjecting saidcircuit in predetermined sequence to a plurality ofconditions, an interlock operable after a predetermined higher number ofrevolutions for retaining said transfer means in a fixed positionirrespective of the completion of said lower number of revolutions,calibrating means, and means operable during only a fraction of saidlower numberof revolutions for including said calibrating means in saidcircuit and for effecting under control of said relay recalibratingadjustment of said circuit, said last-named means thereafter excludingsaid calibrating means from said circuit whereby said relay during theremaining fraction of said lower number of revolutions rebalancessaidcircuit prior to operation of said transfer means.

2. In a self-balancing measuring system including a measuring circuit, adriven member including a circuit adjusting element, a mechanical relayfor driving said adjusting element by a plurality of decreasing steps toa circuit rebalancing position and including a control elementperiodically freed for deflection in accordance with the sense andextent of unbalance of said circuit, relay driving means including adriving shaft, means operable in response to each revolution of saidshaft to free said control element and effect a step-by-step movement ofsaid driven member corresponding to the sense and extent of deflectionof said control element, the combination of transfer means periodicallyoperable from one to another of a plurality of positions aftercompletion of a predetermined low number of revolutions of said shaftfor subjecting said circuit in predetermined sequence to each of aplurality of conditions, calibrating means for said circuit, meansoperable in timed relation with said transfer means for periodicallyrendering said calibrating means effective so that each successiveoperation of said calibrating means occurs for a different position ofsaid transfer means, and means for preventing operation of said transfermeans during operation of said calibrating means.

3. In a self-balancing measuring system including a measuring circuit, asource of supply therefor, a primary member movable from a neutralposition in accordance with variations in magnitude of a condition undermeasurement as determined by said measuring "oircuit,-a secondarymovable member, means operable by said secondary member to rebalancesaid circuit, operating means for said secondary member controlled bysaid primary movable member for periodically actuating said rebalancingmeans to rebalance said measuring circuit, mechanism for periodicallyrecalibrating said measuring circuit comprising means for adjusting anelectrical condition thereof, a standard electrical unit,

circuit controlling means for connecting said standard unit in saidmeasuring circuit in opposition to said source of supply, thecombination of a continuously rotating cam provided with a peripheralrecess, a cam followernormally bearing upon the face of said cam andbiased into said recess, means responsive to theentry of said followerinto said recess for actuating said circult controlling means and foreffecting an interconnection between said secondary movable member andsaid adjusting means, and an auxiliary cam for disengaging saidfollowerv from said recess.

4. In a self-balancing measuring system including a measuring circuit, asource of supply therefor, a primary member movable from a neutralposition in accordance with variations in magnitude of a condition undermeasurement as determined by said measuring circuit, a secondary movablemember, means operable by said secondary member to rebalance saidcircuit, operating means controlled by said primary movable member forperiodically moving said secondary member to effect said rebalance ofsaid measuring circuit, mechanism for periodically recalibrating saidmeasuring circuit comprising means for adjusting an electrical conditionthereof, a standard electrical unit, circuit controlling means forconnecting said standard unit in said measuring circuit; the combinationof a continuously rotating cam provided with a peripheral recess, a camfollower normally bearing upon the face of said cam and biased into saidrecess, means responsive to the entry of said follower into said recessfor actuating said circuit controlling means and for effecting aninterconnection between said secondary movable member and said adjustingmeans, and additional means operating at a higher speed, and of adifferent order of magnitude than said cam, for accurately andadditionally controlling entry of said follower into said recess.

5. In a self-balancing measuring system including a measuring circuit, asource of supply therefor, a galvanometer connected to measure theunbalance of said circuit, a driven shaft, mechanical relay apparatus,including a continuously rotating driving shaft, for periodicallyadjusting said driven shaft under control of said galvanometer, andmeans operated by said driven shaft to rebalance said measuring circuit,mechanism for periodically recalibrating said measuring circuitcomprising means for adjusting an electrical condition thereof, astandard electrical unit, circuit controlling means for connecting saidstandard unit in said measuring circuit, the combination of a rotatablecam, a double-worm gear reduction for driving said cam from said drivingshaft, a cam follower, means responsive to movement of said followerrelative to said cam to actuate said circuit controlling means and toeffect an interconnection between said driven shaft and said adjustingmeans, a second cam driven by the first worm Wheel of said gearreduction, and a follower for said second cam acting conjointly withsaid first follower accurately to phase the operation of said actuatingmeans with respect to the cycle of operation of said mechanical relayapparatus.

6. In a self-balancing measuring system including a measuring circuit, asource of supply therefor, a primary member movable from a neutralposition in accordance with variations in magnitude of a condition undermeasurement as determined by said measuring circuit, a secondary movablemember, means operable by said secondary member for rebalancing saidmeasuring circuit, operating means controlled by said primary movablemember for periodically actuating said rebalancing means to rebalancesaid measuring circuit, mechanism for periodically recalibrating saidmeasuring circuit comprising means for adjusting an electrical conditiontherea means .m '-=uouslyotatingncamprovide'd with a'peripheral recess,a follower-normally; bearing upon the face of said; cam biased into saidrecess, .means'responsive to entry'of. saidfollower into or. a man-d.electrical unit}: circuit controlling n'gi-c'ircui't, the. combinationof a lcontinsaid 'recess for actuating said circuit controlling meansand for effecting. an interconnection be- .tween, said secondary;movable member and said adjusting'meansra second cam rotating con--vtinuously at'a speedfv'ery much higher than said 'flrst mentioned cam,and a cam follower for said second cam actingconjointly withsaid firstfollower accurately totime the operation of said actuating means;

'1. In aself-Qbalancing' measuring system in-v cluding a measuringcircuit, a galvanometer connected to measure the unbalance of saidcircuit,

, a driven shaft, mechanical relay apparatus, in-

cluding a continuously rotating driving shaft, for periodicallyadjusting said driven shaft under control of said galvanometer, andmeans operatedby said'driven shaft to rebalance said measuring circuit,and mechanism operable by, said relay apparatus for periodicallyrecalibrating said measuring circuit including means for adjusting anelectrical condition thereof, the combination of a rotatable cam, adouble-worm gear reduction for driving said cam from said driving shaft,a cam follower, means controlled by said follower to effect aninterconnection between said driven shaft and said adjusting means, asecond cam driven by the intermediate worm wheel of said gear reduction,and a follower for said second cam acting conjointly with said firstfollower accurately to phase the operation of said interconnecting meanswith respect to the cycle of operation of said mechanical relayapparatus.

8. In a self-balancing measuring system including a measuring circuit, aprimary member movable from a neutral position in accordance withvariations in magnitude of a condition under measurement as determinedby said measuring circuit, a secondary rotatable structure includingmeans for rebalancing said circuit, and operating means controlled bysaid primary movable member for operating periodically said secondarystructure to rebalance said measuring circuit, mechanism forperiodically recalibrating said measuring circuit, circuit controllingmeans for completing connections for said recalibration of saidmeasuring ,circuit, and a rotatable adjustable impedance interconnectedwith said measuring circuit, the combination of a support for saidimpedance pivoted aboutan axis parallel to said rotatable structure, andmeans operating intermittently to actuate said circuit controlling meansand to move said support about its pivot to effect a driving engagementbetween said rotatable structure and said rotatable impedance.

9. In a self-balancing measuring system including a measuring circuit, aprimary member movable from a neutral position in accordance withvariations in magnitude of a ctmdition under measurement as determinedby said measuring circuit, including means for rebalancing said circuit,a secondary rotatable structure, means con-o.

trolled by said primary movable member for periodically actuating saidsecondary structure to rebalance said measuring circuit, mechanism forperiodically recalibrating said measuring circuit, circuit controllingmeans for completing recalibrating connections for said measuring cirforconnecting saidrstandard unit in said and biased for movement about itspivotal axis to eflect a driving engagement between said rotatablestructure and said rotatable impedance,

, a oontinuouslyrotating cam, and means includa ing, a camfollower'normally restraining said pivoted support from movement aboutits pivotal 1o axis but intermittently releasing the same forrecalibration of said measuring circuit.

10. In a self-balancing measuring system including a measuring circuit,a primary member movable from a neutral position in accordance withvariations in magnitude of a condition under measurement as determinedby said measuring circuit, a secondary movable member,circuitrebalancing means operable thereby, operating means controlled bysaid primary movable member for periodically operating said secondarymember to rebalance said measuring circuit, mechanism for periodicallyrecalibrating said measuring circuit and including means for adjustingan electrical condition thereof, circuit controlling means forcompleting recalibration connections for said measuring circuit, thecombination of a continuously rotating cam, a cam follower, meanscontrolled by said follower to actuate said circuit controlling means,other means also controlled by said follower to effect aninterconnection between said secondary movable member and said adjustingmeans, a second cam rotatable with said first cam but having anoperating element retarded in phase with respect 5 to that of saidfirst-named cam, and a follower for said second cam controlling saidinterconnecting means conjointly with said first-named cam and follower.

11. In a self-balancing measuring system including a measuring circuit,a primary member movable from a neutral position in accordance withvariations in magnitude of a condition under measurement as determinedby said measuring circuit, a secondary movable structure including meansfor rebalancing said circuit, means controlled by said primary movablemember for periodically operating said secondary structure to rebalanccsaid measuring circuit, mechanism for periodically recalibrating saidmeasuring circuit including means for adjusting an electrical conditionthereof, circuit controlling means for completing recalibratingconnections for said measuring circuit, the combination of a pivotallymounted member biased to move about its pivot and to actuate saidcircuit controlling means, an auxiliary pivotally mounted member biasedto -move about its pivot and to effect an interconnection between saidsecondary movable structure and said adjusting means but normallyrestrained by said first-named pivotally mounted member, a continuouslyrotating cam, means including a cam follower therefor normallyrestraining said first-named pivotally mounted member from motion aboutits pivot and timing its operation, a second cam rotating with saidfirst-named cam but having an operating element retarded in phase withrespect thereto, and

a follower for said second cam normally restraining said auxiliarypivotally mounted member from motion about its pivot and timing itsoperation with respect to that of said first-named pivotally mountedmember.

12. A multiple-point measuring apparatus comprising a rotatablestructure provided with a 15 plurality of spaced peripheral markingelements, a pivotal support for said rotatable structure, means forcarrying a record chart, means supporting said structure and its supportfor displacement across said chart,.actuating mechanism effective uponeach operation thereof to oscillate said support to bring said structureinto registration .with said record chart and including a. ratchet andpawl mechanism operable concurrently with oscillation of said structureinto and out of registration with said chart for rotate ing saidstructure through an angle equal to the angular spacing of said markingelements, a continuously rotating shaft, a cam operated by said shaft,and a cam follower therefor periodically operating said actuatingmechanism.

13. A multiple-point measuring apparatus comprising a rotatablestructure provided with a plurality of spaced peripheral markingelements, a pivotal support for said rotatable structure, a shaftconnected to rotate said structure and along which said support isslidable, means for carrying a record chart, an oscillatable memberhaving a sliding engagement with said support, actuatingmechanism-including a crank secured to said oscillatable member to bringsaid rotatable structure into registration with said record chart and aratchet and pawl mechanism respectively secured to and supported by saidshaft to rotate said structure step-by-step, a continuously rotatingshaft, a cam operated by said continuously rotating shaft, and a camfollower therefor connected to operate said actuating mechanism.

14. In a multiple-point measuring apparatus comprising a rotatablestructure provided with a plurality of spaced peripheral markingelements, a shaft connected to rotate said structure, a carriageslidable along said shaft, means for carrying a record chart, thecombination of a support for said rotatable structure pivotallysupported from said carriage, an oscillatable shaft having alongitudinal slot, said carriage having an element engaging'saidoscillating shaft to prevent rotation of said carriage and said supporthaving an element engaging said slot, actuating mechanism including acrank arm secured to said oscillatable shaft to effect registrationbetween said chart and said structure and a ratchet and pawl mechanismconnected to said first-named shaft to effect step-by-step rotationthereof, a continuously rotating shaft and means operated by saidcontinuously rotating shaft for periodically operating said actuatingmechanism.

15. In a multiple-point measuring apparatus comprising a rotatablestructure provided with a plurality of spaced peripheral markingelements, means for carrying a record chart, means for moving saidstructure with respect to said chart, the combination of an actuatingmechanism effective upon each operation thereof to bring said rotatablestructure into registration with said record chart and to rotate saidstructure through an angle equal to the angular spacing of said markingelements, said mechanism a record chart, means for moving said structurewith respect to said chart, the combination of an actuating mechanismeffective upon each operation thereof to bring said rotatable structureinto registration with said record chart and to rotate said structurethrough an angle equal to the angular spacing of said marking elements,said mechanism including a pivoted lever biased to an operatingposition, a continuously rotating cam, a cam follower thereforperiodically operating said actuating mechanism, a second cam rotatingcontinuously at a speed very much higher than, said first-named cam, anda cam follower for said second cam acting conjointly with said firstfollower accurately to time the operation of said actuating mechanism.

17. In a mechanical relay operated multiplepoint self-=balancingmeasuring system, including a continuously rotating driving shaft, arotatable structure provided with a plurality of spaced peripheralmarking elements, means for carrying a record chart, and means operatedby said driven shaft to move said structure with respect to said chart,the combination of an actuating mechanism effective upon each operationthereof to bring said rotatable structure into registration with saidrecord chart and to rotate said structure through an angle equal to theangular spacing of said marking elements, a rotatable cam operated bysaid driving shaft but at a reduced speed, a cam follower thereforcontrolling the operation of said actuating mechanism, a second camoperated by said driving shaft at a speed of a higher order of magnitudethan said first cam, and a follower for said second cam actingconjointly with said first follower accurately to phase the operation ofsaid actuating mechanism with respect to the cycle of operation of themechanical relay.

18. In a mechanical relay operated multiplepoint self-balancingmeasuring system, including a continuously rotating driving shaft, arotatable structure provided with a plurality of spaced peripheralmarking elements, means for carrying a record chart, means fordisplacing said structure across the chart, the combination of anactuating mechanism effective upon each operation thereof to bring saidrotatable structure into registration with said record chart and torotate said structure through an angle equal to the angular spacing ofsaid marking elements, a rotatable cam, a worm and worm wheel fordriving said cam from said driving shaft, a cam follower thereforcontrolling the operation of said actuating mechanism, a second camsecured to and rotatable with said driving shaft, and a cam follower forsaid second cam acting conjointly with said first follower accurately tophase the operation of said actuating mechanism with respect to thecycle of operation of the mechanical relay.

19. In a multiple-point recorder having a rotatable structure providedwith a plurality of peripherally spaced marking elements, thecombination of a shaft, a carriage slidably supported on said shaft, aframe pivotally mounted from said carriage and having provisions forrotatably supporting said structure, adriving gear rotatable with saidshaft and slidable with said carriage a cooperating driven gearjournaled in said frame and meshing with said driving gear substantiallyat the pivotal axis of said frame for rotating said structure, anelongated member disposed parallel to said shaft, said frame having atleast one extension cooperating with said member to predetermine theposition of said frame,

-ing said print wheel and said structure in synmeans for moving saidmember and by said at least one extension to rotate therewith said framefrom said predetermined. position, and ratchet means supported by saidshaft and operable only upon return movement of said frame to saidpredetermined position for rotating said shaft an amount suflicient todrive said structure an amount equal to the angular displacement betweensaid marking elements.

20. In a multiple-point recorder having a chart-support, a carriage,means mounting said carriage for transverse movement across the chart, aframe pivotally mounted from said carriage, a print wheel journaled insaid frame with its axis of rotation normal to the chart, said printwheel having a plurality of angularly disposed marking elements disposedon a beveled face thereof, and means for actuating said frame to move aselected one of said elements into and out of printing engagement withthe chart.

21. In a multiple-point recorder having a chart-roll disposed adjacentthe front thereof, a carriage, means mounting said carriage fortransverse movement across the chart, a frame pivotally mounted fromsaid carriage, a print wheel journaled in said frame with its axis ofrotation normal to the chart and normal to the pivotal axis of saidframe, and means cooperating with said frame for normally retaining saidprint wheel in a non-printing position, for bodily moving said printwheel downwardly therefrom to a position substantially below the top ofand in front of said roll to print on the-chart a record, and forreturning said wheel to said non-printing position to render immediatelyvisible on said chart said printed record.

22. In a multiple-point recorder having a multiple point recordingelement assembly comprising a rotatable structure provided with aplurality of spaced peripheral marking elements, the combination of acarriage, a support for said structure pivotally mounted from saidcarriage, a driving gear journaled in fixed position with respect tosaid carriage, and a driven gear journaled in said support for rotatingsaid structure and meshing with said driving gear substantially at thepivotal axis of said support.

23. In a multiple-point recorder including a rotatable structureprovided with a plurality of spaced peripheral marking elements, thecombination of a carriage, a support for said structure pivotallymounted from said carriage, an inking device supported from saidcarriage for cooperation with said rotatable structure, and means formoving said support about its pivot to effect a registration of one ofsaid marking elements with a record chart and to effect engagement anddisengagement of one of said elements with said inking device.

24. In a multiple-point recorder including a recording elementassemblycomprising a rotatable print wheel provided with a plurality of spacedperipheral marking elements, the combination of a carriage, a supportfor said print wheel pivotally mounted from. said carriage, a rotatablestructure provided with a plurality of inking pads similar in number andspacing to said marking elements, said structure being pivotallysupported from said carriage in cooperative relation with said markingelements, means for pivotally moving said support to effect engagementand-disengagement of said inking pads and marking elements and to eifectregistration of the latter with a record chart, and means forrotatchronism.

25. In an instrument having a member movable in accordance withunbalance of a balanceable network, the combination of a calibratingimpedance for said network; an arm supporting said impedance formovement into and out of driving engagement with said member, anactuating arm normally biasing said supporting arm to a position toretain said impedance out of engagement with said member, a calibratingswitch for said network operatively. associated with said arm, a controlmember biased towards said actuating arm with sufflcient force tooperate said switch, and releasable means for retaining said controlmember in a position ineffective to cause said operation of said switch.

26. In an instrument having a member movable in accordance withunbalance of a balanceable network, the combination of a three-partcalibrating device, onepart comprising a pivoted switch-actuating arm, asecond part comprising a pivoted support for an impedance device, andthe third part comprising a control arm pivoted about the same axis assaid first part for moving said first part, a spring interconnectingsaid first and second parts, a second spring biasing said first partinto engagement with said second part, and a third spring for movingagainst the bias of said first and second springs said first and thirdparts into switch operating positions,- and means for successivelyreleasing and thereafter moving out of said switch operating positionsaid third part.

27. In an instrument having a member movable in accordance withunbalance of a balanceable network, the combination of an adjustableimpedance, an arm supporting said impedance for movement into and out ofdriving engagement with said member, a switch for completing a circuitincluding said impedance, an actuating arm for said switch normallyengaging said supporting arm to retain it in a position with saidimpedance out of said engagement with said member, a control memberbiased toward said actuating arm with sufficient force to operate saidswitch, releasable means for retaining said control member in a positionineil'ective to cause operation of said switch actuating arm, saidcontrol member upon release thereof operating said actuating arm toactuate said switch, and means for retaining said supporting arm in aposition with its said impedance out of said driving engagement for atime interval after operation of said switch by said actuating arm.

28. In an instrument having a member movable in accordance withunbalance of a balanceable network, the combination of an adjustableimpedance, an arm supporting said impedance for movement into and out ofdriving engagement with said member, a switch for completing a circuitincluding said impedance, an actuating arm for said switch biased to afirst switch-operating position and normally engaging said supportingarm to retain said impedance out of said driving engagement, a controlmember biased for movement into engagement with said actuating arm withsuflicient force to move said arm against its bias to a secondswitch-operating position, afirst cam releasably retaining said controlmember in a position to prevent operation of said switch to its secondposition, a second cam releasably retaining said supporting arm and itsimpedance out of said driving engagement, means for driving said camswith said second

